Abstract:

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The present paper provides plastic limit load solutions for axial and circumferential
through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis
using elastic-perfectly plastic behavior. As a loading condition, both single and combined loadings are
considered. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be
valuable information for structural integrity assessment of cracked pipes.

Abstract: Tube hydroforming technology is still considered a new technique growing fast in automotive and aircraft industries. Many researches on all aspects of this process are still required. Contact friction is one of the most effective parameters on tube wall thinning. To successfully fulfill the process without any common defects, it is very important to determine the proper internal pressure and axial feeding loading paths. In this paper, the effect of lubrication on tube wall thinning on ASTM C11000 copper alloy is discussed as well as the effect of internal pressure and axial feeding. An axisymmetric bulged tube is investigated using theoretical, numerical and experimental methods. Improved linear and non-linear pressure and feeding loading paths are applied and the predicted results are experimentally proved. It is observed that non-linear pressure application gives smoother results. Also proper lubrication plays an important role in success of the process.

Abstract: A blood vessel model of pseudo-elastic constitutive relation in an absolute (vacuum) zero-stress state is employed, and analytical equations of the vessel wall in the three-dimensional stress state are obtained in this paper. The stress distributions in circumferential and axial directions with different blood pressure levels and material parameters are discussed. The results show that the initial stresses of the vessel wall will increase with increment of the blood pressure, the material parameters also affect the distributions of initial stress, in particular, the increase of axial material parameters, will significantly increase axial stress. These methods are importance in the investigation of the vascular dynamic problem, and conclusions are of use in prevention of the related vascular diseases.

Abstract: According to energy principle, numerical methods of axial force and displacement of tension-type anchor are derived. Firstly, mechanism of tension-type, computation model of anchoring unit and side resistance are discussed. Secondly, anchoring unit energy balance equations are derived, and given the difference form. Thirdly, program calculation method and program convergence strategy are illustrated. At last, anchor bearing character is analyzed. The main conclusions are: anchorage body bearing character could be reasonably analyzed by using the energy method. The analysis results can provide the reference for engineering design.

Abstract: It is necessary to know the connecting and sealing ability of premium connection for appropriate choices of different working conditions. By finite element method, the finite element model of premium connection is established and the stresses of seal section, shoulder zone and thread surface of tubing by axial tensile loads are analyzed. The results show that shoulder zone is subject to most axial stresses at made-up state, which will make distribution of stresses on thread reasonable. With the increase of axial tensile loads, stresses of thread on both ends increase and on seal section and shoulder zone slightly change. The maximum stress on some thread exceed the yield limit of material when axial tensile loads exceed 400KN. Limited axial tensile loads sharply influence the contact pressures on shoulder zone while slightly on seal section. Although the maximum contact pressure on shoulder zone drop to 0 when the axial tensile load is 600KN, the maximum contact pressure on seal section will keep on a high level.

Abstract: According to the actual structure of submarine flexible pipe, considering the combined effect of internal pressure and transverse load by wave-current flow that is based on 50 year return period wave statistics data of Cheng Dao sea area, ANSYS finite element model of flexible pipe is established. The influence of internal pressure and suspension length on the axial stress of steel wire reinforcement layer and the Mises stress of rubber layer was analyzed. Comparatively, suspension is the main cause for the failure of steel submarine pipeline, but could hardly lead to the failure of submarine flexible pipe, which shows that flexible pipe is stronger applicable for submarine pipeline.